Knowledge Resource Center for Ecological Environment in Arid Area
| 藏北高原毒杂草的空间分布格局及治理研究 | |
| 其他题名 | Spatial Patterns and Governance of Poisonous Plants on the Northern Tibetan Plateau |
| 杨鹏万 | |
| 出版年 | 2015 |
| 学位类型 | 硕士 |
| 导师 | 沈振西 |
| 学位授予单位 | 中国科学院大学 |
| 中文摘要 | 藏北高原高寒草地是西藏自治区乃至全中国的重要生态安全屏障，促进该区域的退化草地的恢复重建是西藏自治区最为迫切的任务之一。 为了探究草地退化的空间格局及其驱动因素，本研究以藏北天然草地的可食牧草与毒杂草的物种丰富度比值、盖度比值、地上生物量比值为指标，在2009-2012年共调查了75个放牧样地（33个在高寒草甸，28个在高寒草原，14个在高寒荒漠草原），分析这3个指标与生长季降水、放牧强度的关系，结果表明： （1）区域上的毒杂草型退化草地的空间分布格局是由生长季的降雨决定的。在生长季降雨量为250-350mm下的半干旱的高寒草原地区，就物种多样性、盖度和地上生物量这三种指标而言，毒杂草所占的比例最高；而在湿润的高寒草甸或者更加干旱的高寒荒漠草原则是毒杂草比例较低。 （2）在毒杂草型退化草地中可食牧草与毒杂草的物种丰富度比值、盖度比值和地上生物量比值随着生长季降水的增加呈先减小后增大的二次曲线趋势（P < 0.0001）。 （3）可食牧草与毒杂草的物种丰富度比值和放牧率之间没有明显的相关关系（P = 0.9722）；而可食物种与不可食物种的盖度比值和地上生物量比值均与采样点附近的放牧率为显著的正相关关系（P < 0.0001）。 在气候持续变暖的背景下，过度放牧必将导致特定毒杂草在天然草地的入侵和拓殖，从而影响高寒草地的物种组成，进而影响生态系统过程和功能。为了提出具体的生态恢复措施，本研究2012年在藏北高原中部尼玛县设置了以冰川棘豆（Oxytropis glacialis）为主要入侵种的退化草地治理试验，探讨补播、施肥及剔除对高寒退化草地的改良效果。结果表明： （1）补播、施肥、剔除都可以有效地减少毒杂草的盖度和地上生物量的相对比重，从生态修复的角度考虑，施肥是最优的措施，因为施肥不仅可以抑制毒杂草的生长（毒杂草盖度相对比重下降61.27%，地上生物量相对比重下降44.83%），还可以极大地提高牧草的地上生物量（增加114.92%）。 （2）同时施加补播、施肥、剔除这三项措施能达到最好的治理效果，它可以使毒杂草的盖度相对比重下降88.62%，地上生物量相对比重下降70.16%，牧草地上生物量增加184%。 |
| 英文摘要 | The alpine grasslands on the Tibetan Plateau provide ecological security for the local and surrounding regions, and promoting the recovery of the degraded grasslands is one of the most serious challenge currently being faced by the developing Tibetan Autonomous Region. Field surveys of 75 grazing sites were conducted during 2009-2012 in the Changtang Nature Reserve and d escribed the spatial pattern of grassland degradation which was caused directly by poisonous locoweeds along a gradient of growing season precipitation (GSP) at a regional scale. The study results are as follows: (1) There were higher ratios of species richness, coverage and aboveground biomass of poisonous plants compared with non-poisonous plants in the semi-arid alpine steppe zone where GSP is between 250 mm and 350 mm; however, this finding was in contrast to the relatively wetter meadow and much drier desert-steppe communities. (2) The precipitation gradient was primarily responsible for the quadratic trends (initially increasing and then decreasing) of compositional changes in the poisonous species compared with non-poisonous species. (3) The species richness, coverage, and biomass of both non-poisonous and poisonous plants are positively related to growing season precipitation. Non-poisonous plants exhibit exponential growth patterns, and poisonous plants show positive linear regressions (P < 0.0001). However, significant quadratic patterns have been found for the non-poisonous to poisonous ratios for richness, coverage and biomass along the increasing precipitation gradient across the Northern Tibetan Plateau (P < 0.0001). Along with climatic warming, overgrazing may result in the invasion and brooms of some poisonous plants in the natural grasslands. In order to put forward the concrete measures of ecological restoration, an experimental site where Oxytropis glacialis raging was set up to investigate the effects of reseeding, fertilization and elimination on the vegetation recovery of degraded grassland. The results show that the reseeding、fertilization、elimination all can effectively reduce the poisonous weeds in the proportion of coverage and aboveground biomass. Considering from the angle of ecological restoration, fertilization was the best measure, because fertilization can not only inhibited the growth of poisonous weeds, but also can improve the alpine grassland productivity greatly. While all the three measures were applied together, the best effect was achieved, the noxious weeds coverage ratio dropped by 88.62% and aboveground biomass ratio dropped by 70.16%, and the grass aboveground biomass increased 184%.. |
| 中文关键词 | 高寒草地 ; 毒杂草 ; 空间分布格局 ; 放牧 ; 退化草地治理 |
| 英文关键词 | Alpine grasslands Poisonous plants Spatial patterns Grazing management Rangeland governance |
| 语种 | 中文 |
| 国家 | 中国 |
| 来源学科分类 | 生态学 |
| 来源机构 | 中国科学院地理科学与资源研究所 |
| 资源类型 | 学位论文 |
| 条目标识符 | http://119.78.100.177/qdio/handle/2XILL650/287486 |
| 推荐引用方式 GB/T 7714 | 杨鹏万. 藏北高原毒杂草的空间分布格局及治理研究[D]. 中国科学院大学,2015. |
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